This applet features two wagons which can undergo a collision that is either totally elastic or totally inelastic. The simulation is complex enough to allow users to set mass and initial velocity, but simple enough to promote student understanding of physical interactions in colliding systems.

Lots of factors are at play in a simple collision. This resource will help your students build understanding the of following: 1) How to apply the law of momentum conservation, 2) Total energy in a closed system (it's always conserved, but in collisions, kinetic energy is generally transformed into other forms of energy), 3) In special cases (perfectly elastic collisions) the kinetic energy stays the same before and after a collision, 4) In completely inelastic collisions, objects stick together, 5) momentum is a vector.

Content Support For Teachers:

In this 2001 paper presented at the Physics Education Research Conference, authors describe the effects of two teaching approaches in a classroom lab on momentum: microcomputer-based labs (MBR) and video-based labs (VBR). Results indicate that students made good use of the information in the lab, and that they spent more time talking about concepts involving conservation of momentum and energy.

Assessment:

This high-school-level assessment gauges student understanding of using diagrams to predict outcomes in colliding systems. It is intended for use in a unit on the conservation of linear momentum. The student assessment is printable, and an answer key is included.

Activities:

This entertaining mini-lesson developed by Exploratorium engages the learner in physical activity to explore the effects of a twisting force (torque) on rotational motion. By mimicking the motion of a skateboarder, students gain intuitive understanding of the law of conservation of angular momentum.

This inquiry-based activity challenges students to apply their understanding of momentum and collision to determine who is at fault in an automobile accident. It would be especially appropriate for cooperative learning groups.

Content Support For Teachers:

This PTRA manual presents the physics of impulse and momentum and learning materials to help students with this topic. Samples from the full print manual are available here. In this book, a section on theory and applications is followed by laboratory, classroom, and computer activities. The manual also includes a section on modern physics applications of the topic. Assessment questions are also provided for use by instructors.

Lesson Plans:

Auto collisions offer a concrete way to think about conservation of linear momentum. In this PBL activity, students must figure out who is at fault in a T-bone collision, given little more than the angle of impact, size of the dent, and the extent of seat-belt laceration injuries of one driver. The student guide may be freely accessed; registration is required to download the teacher's guide with lesson plan.

Activities:

Students work cooperatively to investigate an accident: a small car is struck broadside by a vehicle more than double its mass. The students must determine whether either driver engaged in reckless driving. More than one strategy can be used to solve the problem, which requires students to find the coefficient of friction on the roadway and determine the velocity of each vehicle upon impact and before braking. (It will be interesting to see if students choose the Work-Energy Theorem in solving.) A complete instructor's guide is available cost-free to teachers who register on the web site.

This simulation is a good starting point for learning about collision, as students observe two particles move and collide in one dimension. The collision is elastic -- caused by a virtual spring. Students can set starting velocities and spring constant, then view graphs of momentum and kinetic energy alongside the simulation. Editor's Note In the middle school classroom, this item could also serve well as a teacher-led demonstration, with students predicting the motion and graph changes as velocity and spring constant are changed.

Nobody will snooze through this 22-minute video, narrated by high school physics teacher Griff Jones. It explores the fundamentals of momentum/impulse through vehicle crashes on test tracks at the Insurance Institute for Highway Safety. Don't miss the accompanying Teacher's Guide with lessons & assessments for doing a complete unit on collisions.